diff options
Diffstat (limited to 'absl/debugging/internal/stacktrace_x86-inl.inc')
| -rw-r--r-- | absl/debugging/internal/stacktrace_x86-inl.inc | 29 |
1 files changed, 26 insertions, 3 deletions
diff --git a/absl/debugging/internal/stacktrace_x86-inl.inc b/absl/debugging/internal/stacktrace_x86-inl.inc index 9fbfcf76..1975ba74 100644 --- a/absl/debugging/internal/stacktrace_x86-inl.inc +++ b/absl/debugging/internal/stacktrace_x86-inl.inc @@ -29,6 +29,7 @@ #include <cstdint> #include <limits> +#include "absl/base/attributes.h" #include "absl/base/macros.h" #include "absl/base/port.h" #include "absl/debugging/internal/address_is_readable.h" @@ -39,7 +40,7 @@ using absl::debugging_internal::AddressIsReadable; #if defined(__linux__) && defined(__i386__) // Count "push %reg" instructions in VDSO __kernel_vsyscall(), -// preceeding "syscall" or "sysenter". +// preceding "syscall" or "sysenter". // If __kernel_vsyscall uses frame pointer, answer 0. // // kMaxBytes tells how many instruction bytes of __kernel_vsyscall @@ -111,6 +112,10 @@ static int CountPushInstructions(const unsigned char *const addr) { // Assume stack frames larger than 100,000 bytes are bogus. static const int kMaxFrameBytes = 100000; +// Stack end to use when we don't know the actual stack end +// (effectively just the end of address space). +constexpr uintptr_t kUnknownStackEnd = + std::numeric_limits<size_t>::max() - sizeof(void *); // Returns the stack frame pointer from signal context, 0 if unknown. // vuc is a ucontext_t *. We use void* to avoid the use @@ -257,8 +262,26 @@ static void **NextStackFrame(void **old_fp, const void *uc, // With the stack growing downwards, older stack frame must be // at a greater address that the current one. if (new_fp_u <= old_fp_u) return nullptr; - if (new_fp_u - old_fp_u > kMaxFrameBytes) return nullptr; + // If we get a very large frame size, it may be an indication that we + // guessed frame pointers incorrectly and now risk a paging fault + // dereferencing a wrong frame pointer. Or maybe not because large frames + // are possible as well. The main stack is assumed to be readable, + // so we assume the large frame is legit if we know the real stack bounds + // and are within the stack. + if (new_fp_u - old_fp_u > kMaxFrameBytes) { + if (stack_high < kUnknownStackEnd && + static_cast<size_t>(getpagesize()) < stack_low) { + // Stack bounds are known. + if (!(stack_low < new_fp_u && new_fp_u <= stack_high)) { + // new_fp_u is not within the known stack. + return nullptr; + } + } else { + // Stack bounds are unknown, prefer truncated stack to possible crash. + return nullptr; + } + } if (stack_low < old_fp_u && old_fp_u <= stack_high) { // Old BP was in the expected stack region... if (!(stack_low < new_fp_u && new_fp_u <= stack_high)) { @@ -311,7 +334,7 @@ static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count, // Assume that the first page is not stack. size_t stack_low = static_cast<size_t>(getpagesize()); - size_t stack_high = std::numeric_limits<size_t>::max() - sizeof(void *); + size_t stack_high = kUnknownStackEnd; while (fp && n < max_depth) { if (*(fp + 1) == reinterpret_cast<void *>(0)) { |